1. Field of the Invention
The present invention relates generally to apparatus and a method for forming splines in an annular thin wall power transmission member, and more particularly to such apparatus and a method which incorporate a toothed pinion type mandrel for mounting the power transmission member to the splined and also incorporate a pair of cooperable dies that are driven on opposite sides of the mandrel mounted member to mesh with the mandrel teeth with the member therebetween in a manner that provides the spline formation.
2. Description of the Prior Art
United States patent application Ser. No. 606,398, filed Aug. 21, 1975 and assigned to the assignee of the present invention, and now U.S. Pat. No. 3,982,415, the entire disclosure of which is hereby incorporated by reference, discloses apparatus and a method for splining power transmission members. A toothed mandrel and a pair of cooperable dies of the apparatus are used in the spline forming operation disclosed. An annular thin wall power transmission member to be splined is mounted on the toothed mandrel and rotatably supported thereby between opposed forming faces of the dies. Die teeth spaced along the forming faces mesh with teeth of the mandrel during die movement with the power transmission member therebetween so as to form the splines.
Certain annular power transmission members, such as clutch hubs, include an end wall and an axial sleeve portion projecting from the end wall with an open end defined opposite the end wall. In splining the sleeve portion of such annular power transmission members, it is important not only to form accurate splines but also to maintain the roundness of the sleeve portion. Adjacent the end wall, the sleeve portion is more rigid than adjacent its open end. This difference in rigidity makes it difficult to maintain the sleeve portion diameter without forming a "bell mouth" shape that is of a larger diameter at the open end of the sleeve portion than adjacent the end wall. Also, it is difficult to maintain the sleeve portion roundness with a constant diameter in all radial directions when splines are formed therein with this toothed mandrel and cooperable dies splining operation. This is particularly the case when the splines being formed are relatively shallow, i.e. of a depth less than twice the thickness of the sleeve portion being splined.
Formation of precise splines on uniform diameter power transmission members is important since these splines must mate with other power transmission components to transfer rotary power. For example, with the clutch hubs previously discussed, clutch discs are stacked and have splines that mate with the splines of the clutch hub sleeve portion. The clutch discs may be located within the sleeve portion so that their outer peripheries are splined to mate with the interior of the splined sleeve portion or, conversely, the clutch discs may have central openings that receive the sleeve portion and are splined to mate with the exterior of the sleeve portion.
United States patents relating to splining or other similar forming are: U.S. Pat. Nos. 1,670,476; 2,886,990; 2,994,237; 3,015,243; 3,407,638; 3,630,058; and 3,672,203.